Multiport usb charger

ABSTRACT

A universal serial bus charging device for charging connected electronic devices is presented. The universal serial bus includes a microprocessor and a power supply configured to output a total charging current. The universal serial bus charging device further includes a plurality of low voltage ports in communication with the microprocessor and electrically coupled to the power supply. Each of the plurality of low voltage ports are capable of connecting with the electronic devices and providing the electronic devices a device charging current. The microprocessor is configured to enumerate the connected electronic devices and communicate to each of the enumerated electronic devices the device charging current available through its respective low voltage port connection. The available device charging current for each enumerated electronic device is determined by the microprocessor as a function of a total charging current and the enumerated electronic devices.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application Ser. No. 61/860,646 filed on Oct. 14, 2013, theentire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a multiport Universal Serial Bus (USB)charger. More particularly, the present disclosure relates to amultiport USB charger configured to limit charging current to devicesattached to the multiport USB charger when the device's charging currentrequest exceeds the charging current capabilities of the multiport USBcharger.

2. Description of Related Art

Due to proliferation of various rechargeable consumer electronicdevices, such as cell phones, laptops, tablets, personal digitalassistants (PDA's), and the like, there is a need to charge and/orconnect to such devices. Most of these devices are powered by lowvoltage and recharging these devices may be facilitated through the useof standard interfaces such as a Universal Serial Bus (USB) chargingdevice. Such charging devices may be designed to charge multipleelectronic devices simultaneously.

However, when multiple devices are coupled to the USB charging device,the charging current requested by each of the electronic devices mayexceed an output charging current capacity of the USB charging device.Conventional USB charging devices remedy this situation by limitingcurrent flow to a channel that supplies the charging current to the USBport that the electronic device(s) is/are attached. Limiting chargingcurrent in this manner, however, can lead to the USB charging deviceoverheating, which, in turn, can lead to channel shut down and/or theUSB charging device not functioning as intended.

SUMMARY

As can be appreciated, a multiport USB charger configured to limitcharging current to a device attached to the multiport USB charger whenthe device's charging current request exceeds the charging currentcapabilities of the multiport USB charger may prove useful in therelated arts.

Embodiments of the present disclosure are described in detail withreference to the drawing figures wherein like reference numeralsidentify similar or identical elements.

An aspect of the present disclosure provides a universal serial bus(USB) charging device that includes a microprocessor, a power supplyconfigured to output a total charging current, and a plurality of lowvoltage ports in communication with the microprocessor and electricallycoupled to the power supply, each of the plurality of low voltage portsbeing capable of connecting with the electronic devices and providingthe electronic devices a device charging current. The microprocessor isconfigured to enumerate the connected electronic devices and communicateto each of the enumerated electronic devices the device charging currentavailable through its respective low voltage port connection. Theavailable device charging current for each enumerated electronic deviceis determined by the microprocessor as a function of the total chargingcurrent and the enumerated electronic devices.

In another aspect of the present disclosure, as one or more of theelectronic devices are connected/disconnected from the plurality of lowvoltage ports, the microprocessor is configured to re-enumerate theconnected electronic devices and communicate to each of there-enumerated electronic devices a redetermined device charging currentavailable through its respective low voltage port connection.

In yet another aspect of the present disclosure, the availableredetermined device charging current for each re-enumerated electronicdevice is determined by the microprocessor as a function of the totalcharging current and the re-enumerated electronic devices.

In yet another aspect of the present disclosure, the microprocessor isconfigured to continuously re-enumerate and redetermine as one or moreof the electronic devices are connected/disconnected to/from theplurality of low voltage ports.

In yet another aspect of the present disclosure, the plurality of lowvoltage ports include a microchip which is connected to a resistivevoltage divider network. The resistive voltage divider network includesa first resistive branch including at least one resistor and a secondresistive branch including at least three resistors.

Logic circuitry associated with the first resistive branch is configuredto ensure that the current does not exceed a maximum current threshold.Logic circuitry associated with the second resistive branch isconfigured to ensure that the current does not fall below a minimumcurrent threshold.

In yet another aspect of the present disclosure, the microprocessor isprogrammed to measure voltage of the power supply of the universalserial bus charging device such that if a voltage output of the powersupply falls below a nominal value, the microprocessor eitherdisconnects one or more of the plurality of low voltage ports orswitches to a disconnect mode.

Another aspect of the present disclosure provides a multiport universalserial bus charging device. The multiport universal serial bus chargingdevice includes a microprocessor, a power supply configured to output atotal charging current, and a plurality of low voltage ports each incommunication with the microprocessor and electrically coupled to thepower supply. The microprocessor is configured to enumerate theconnected electronic devices and communicate to each of the enumeratedelectronic devices, the device charging current available through itsrespective low voltage port connection.

Each respective resistive voltage divider network may include a firstresistive branch including at least one resistor and a second resistivebranch including at least three resistors. The at least one outputsignal is indicative of a current measured along the second resistivebranch of the respective voltage divider network.

Logic circuitry associated with the first resistive branch of therespective voltage divider networks may be configured to ensure thatcurrent does not exceed a maximum threshold. Similarly, logic circuitryassociated with the second resistive branch of the respective voltagedivider networks may be configured to ensure that current does not fallbelow a minimum threshold.

The multiport universal serial port charging device may include a powersupply configured to provide ten (10) watts of power and two (2) amps ofcharging current. In this instance, the plurality of low voltage portsmay include first and second low voltage ports. Each of the first andsecond low voltage ports may be capable of providing one (1) amp ofcharging current to electronic devices attached thereto.

The multiport universal serial port charging device may include a powersupply configured to provide twenty (20) watts of power and four (4)amps of charging current. In this instance, the plurality of low voltageports may include first, second, third, and fourth low voltage ports.Each of the first, second, third, and fourth low voltage ports may becapable of providing one (1) amp of charging current to electronicdevices attached thereto.

The microprocessor may be programmed to measure voltage of a powersupply of the multiport universal serial bus charging device such thatif a voltage output of the power supply falls below a nominal value, themicroprocessor either disconnects one of the plurality of low voltageports or switches to a disconnect mode.

Another aspect of the present disclosure provides a method for chargingmultiple portable devices attached to a multiport universal serial buscharging device. A charging current draw from the multiple portabledevices attached to the multiport universal serial bus charging deviceis compared with a maximum charging current capacity of the multiportuniversal serial bus charging device. If the combined charging currentdraw from the multiple portable devices is greater than the maximumcharging current capacity of the multiport universal serial bus chargingdevice, the charging current draw of at least one of the portabledevices is renegotiated so that the combined charging current draw fromthe multiple portable devices does not exceed the maximum chargingcurrent capacity of the multiport universal serial bus charging device.

BRIEF DESCRIPTION OF THE DRAWING

Various embodiments of the present disclosure are described herein belowwith references to the drawings, wherein:

FIG. 1 is a perspective view of a multiport Universal Serial Bus (USB)charger according to an embodiment of the present disclosure;

FIG. 2 is an exploded view of the multiport USB charger shown in FIG. 1with a face structure and a strap removed to illustrate a logic printedcircuit board (PCB) and a power PCB of the multiport USB charger;

FIG. 3 is a wiring diagram of the circuitry of the multiport USB chargershown in FIG. 1; and

FIG. 3A shows in greater detail the circuitry identified by “3A’ in FIG.3;

FIG. 3B shows in greater detail the circuitry identified by “3B” in FIG.3;

FIG. 3C shows in greater detail the circuitry identified by “3C” in FIG.3; and

FIG. 4 is a block diagram of the multiport USB charger shown in FIG. 1and various portable devices that may be attached to the multiport USBcharger.

DETAILED DESCRIPTION

Detailed embodiments of the present disclosure are disclosed herein;however, the disclosed embodiments are merely examples of thedisclosure, which may be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

As described above, a multiport USB charger configured to limit chargingcurrent to a device attached to the multiport USB charger when thedevice's charging current request exceeds the charging currentcapabilities of the multiport USB charger may prove useful in therelated arts, and such a multiport USB charger is described herein.

FIG. 1 illustrates a multiport USB charging device 10 that includes fourvertically oriented low voltage port apertures (e.g., USB chargingports) 12, 14, 16, and 18. Wiring device 10 includes a generallyrectangular face 20 and the area of face 20 includes a longitudinal axisα and a lateral axis β. Longitudinal axis α bisects the area of face 20parallel to the long dimension of the face dividing the face into rightand left regions. Lateral axis β bisects the area of the face 20parallel to the short dimension of the face, dividing the face into topand bottom regions. Lateral axis β is at a right angle to longitudinalaxis α.

Face 20 includes a first region 22 (e.g., a top half) and a secondregion 24 (e.g., a bottom half) located on opposite sides of lateralaxis β. First region 22 of face 20 includes the first and second lowvoltage port apertures 12 and 14. First low voltage port aperture 12 iselongated along an axis which is parallel to longitudinal axis α. Secondlow voltage port aperture 14 is also elongated along an axis which isparallel to longitudinal axis α. Both first and second low voltage portports 12 and 14 are offset from longitudinal axis α. Offsetting firstand second low voltage port apertures 12 and 14 from longitudinal axis αresults in a neater and more attractive appearance. Likewise, secondregion 24 located on face 20 and includes the third and fourth lowvoltage port apertures 16 and 18, each of which is similarly offsetfrom, and elongated along a respective axis parallel to, longitudinalaxis α.

Referring to FIG. 2, the multiport USB charging device 10 includes firstand second printed circuit boards (PCBs) 26 and 28. First PCB 26 is alogic PCB and second PCB 28 is a power PCB. First PCB 26 includes atleast one low voltage port. In the illustrated embodiment, the first PCB26 is shown including first, second, third, and fourth low voltage ports30, 32, 34, 36, which align with respective low voltage port apertures12, 14, 16, and 18. In the illustrated embodiment, the low voltage ports30, 32, 34, 36 are USB charging ports, which can be configured asdedicated charging ports (DCPs), charging downstream ports (CDPs),and/or standard downstream ports (SDPs). However, low voltage ports 30,32, 34, and 36, can be of any suitable type or combination of types.Second PCB 28 preferably is a power PCB and receives line voltage fromconductors 38 and 40 (e.g. Phase and Neutral). The conductors 38 and 40can be connected directly to a power line, such as, for example, if themultiport USB charging device 10 is to be wall mounted. Alternatively,the conductors 38 and 40 can have a standard plug configuration forconnection with a standard wall receptacle.

First and second PCBs 26 and 28 are joined together at a right angletherebetween, without intervening material. The first and second PCBs 26and 28 can be joined by any suitable method including but not limited tosoldering, adhesive, etc. Joining the PCBs 26 and 28 in this mannermakes for efficient use of the volume within the housing, simplifiedmanufacture, and reduced cost. Alternatively, first and second PCBs 26and 28 can be electrically connected together through any suitablemedium such as, but not limited, to PCB connector(s), wires, bus bars,or any combination thereof. Alternatively, in another exemplaryembodiment, all components may be mounted on a single PCB. To facilitatethe electrical and/or mechanical connection of first and second PCBs 26and 28, the first PCB 26 includes PCB tabs 42, which are received by PCBconnection apertures (not shown in detail) on second PCB 28.

The multiport USB charging device 10 includes circuitry 48 (FIG. 3) usedto transform line voltage from an external source (e.g., an outlet notshown) to low voltage. This circuitry 48 may reside on the first PCB 26and/or second PCB 28. Alternatively, the line to low voltagetransformation circuitry may reside at any other suitable location. Thecircuitry 48 receives power from the external source and distributespower to the components of the multiport USB charging device 10. Inembodiments, the multiport USB charging device 10 is configured tooperate using nominal DC power, e.g., about 5V, which is provided to themultiport USB charging device 10 by the external source. In embodiments,the multiport USB charging device 10 is compliant with the requirementof USB 2.0, which specifies that the output voltage should be between4.75 and 5.25 V DC.

Referring to FIG. 3, the circuitry 48 is illustrated. The circuitry 48is configured to charge various rechargeable consumer electronic devices(see FIG. 4 for example), e.g., portable devices such as cell phones“CPs”, laptops “LTs”, tablets “Ts”, personal digital assistants(“PDAs”), etc.

In accordance with the present disclosure, the circuitry 48 isconfigured to limit power requested by the portable device, e.g.,tablets “T”, not by limiting current within the multiport USB chargingdevice 10, which eventually increases temperature and causes channels toshut down, but by re-negotiating power demand of the portable device.With this purpose in mind, each of the low voltage ports 30, 32, 34, and36 includes a resistive voltage divider network that is connected to amicrochip associated with each of the low voltage ports 30, 32, 34, and36, which enables a microprocessor 51 (e.g., microchip U5) of themultiport USB charging device 10 to measure a current range (e.g., notcharging; less than 0.5 a; within a range from about 0.5 a-1 a; andgreater than 1 a) of the low voltage ports 30, 32, 34, and 36.

Continuing with reference to FIG. 3, each of the low voltage ports 30,32, 34, and 36 includes respective circuits 50, 52, 54, and 56, whichcommunicate various signals to the microprocessor 51. Because therespective circuits 50, 52, 54, and 56 are identical to one another, andso as not to obscure the present disclosure with unnecessary detail,only the circuit 50 of the low voltage port 30 is described herein indetail.

Circuit 50 includes a resistive voltage divider network 58 whichincludes a first resistive branch 60 including a resistor R18 having anohm rating of about 22.1K. The first resistive branch 60 is electricallyconnected to a pin 16 of a microchip U2 of the circuit 50 and to groundGND.

Circuit 50 also includes a second resistive branch 62. The secondresistive branch 62 includes resistors R15, R16 each having an ohmrating of about 51K and a resistor R11 having an ohm rating of about470K. The resistors R15, R16, and R11 are connected in series with oneanother. The second resistive branch 62 is electrically connected to apin 15 of the microchip U2 and to GND.

Resistors connected to pins 15 and 16 are used to set the high and lowcurrent limits, namely, ILIMI_LO and ILIMI_HI. No current value isdirectly measured on these pins. The current is measured indirectly bychanging the resistor value of the divider connected to pin 15 andreading the value of the STATUS pin. The value of the STATUS pin is theresult of comparison of the real charging current and the set ILIMI_LO.If the charging current is higher than the ILIMI_LO threshold, itsoutput is LOW, and when the load current is lower than the limit, theoutput is HIGH.

When a portable device is attached to the low voltage port 30, a voltagemeasurement is taken across resistor R11 to GND and a signal LO2A iscommunicated to pin 23 of the microprocessor 51. Simultaneously, avoltage measurement is also taken across R15 to GND and a signal LO1A iscommunicated to pin 24 of the microprocessor 51, which then utilizessignals LO1A, LO2A to determine if a current is within a predeterminedthreshold value.

LO2A and LO1A are outputs from the microprocessor 51. The microprocessor51 keeps them in a high impedance state (e.g., pull LO2A to the GND orLO1A to the GND). This configuration changes the resistor value, whichdefines a threshold for a current comparator. Based on this threshold,the chip generates an output on the STAT_A line. Each resistor valuematches one of the current levels through the chip. Thus, bymanipulating LO1A and LO2A, the microprocessor 51 can range the currentgoing through the chip and then decide what mode is set for the chip inorder to control the current.

Status pin 9 of the microchip U2 is electrically connected to themicroprocessor 51 and logic circuitry associated with the pin 9generates a status signal STAT_A that is communicated from the statuspin 9 to a pin 21 of the microprocessor 51. The status signal STAT_A iscommunicated to the microprocessor 51 when a portable device isinitially attached to and requesting charging current from the lowvoltage port 30. In embodiments, the microprocessor 51 receives inputfrom each iteration of the circuit 50 to enable the microprocessor 51 toobtain a charge status of portable device attached to the low voltageport 30.

A receptacle, e.g., junction J2, of the low voltage port 30 attaches toa plug of a portable device and includes a four (4) pin configuration.In embodiments, the junction J2 may be configured as a μ−B or a μ−ABreceptacle. Pin 1 of the junction J2 connects to OUT pin 12 (e.g., VBUS)of the microchip U2 and is one of the power pins of the low voltage port30. Pin 4 of the junction J2 is the other power pin and connects to GND.Pins 2 and 3 connect to DM_IN (e.g., D−) and DP_IN (e.g., D+) pins 11and 10, respectively. DM_IN pin 10 and DP_IN pin 11 are differentialdata pins (data pins) often referred to as D+ and D−, which are usedwhen communication and data transfer (e.g., communications) takes placebetween the multiport USB charging device 10 and an attached portabledevice.

The DM_IN pin 10 and DP_IN pin 11 data pins are configured to allow ahandshake to occur when a portable device is attached to the low voltageport 30. In accordance with the instant disclosure, this handshake caninclude the microprocessor 51 communicating with the attached portabledevice to enable the portable device itself to determine how muchcurrent to draw from the maximum current available, as will be describedin detail below. In embodiments according to the present disclosure, themicroprocessor 51 informs the portable device of the maximum amount ofcurrent it can draw and permits the portable device itself to eitherdraw the maximum amount of current or draw an amount less than themaximum amount of current. This allows the portable device toself-regulate how much current to draw based on the maximum currentavailable. In other words, the microprocessor 51 does not control theamount of power available to each portable device and does not activelyregulate the flow of current. How much current each portable device candraw is determined by the portable device itself based on the maximumcurrent available. The maximum current is computed by the microprocessor51.

Control signal CTL 2,3A is output from CTL2 pin 7 and CTL3 pin 8 of themicrochip U2 to PD2 pin 27 of the microprocessor 51. Similarly, controlsignal CTL1A is output from CTL 1 pin 6 of the microchip U2 to PD3 pin28 of the microprocessor 51. The control signals CTL 2,3A and CTL1Aswitch the chip to one of modes DCP, CDP or discharge, and in each modenegotiation with the attached device, yield different charging current.

The other components of the circuit 50 are standard components in USBports, and a detailed description of how these components operate hasnot been provided as their configuration and operation would be known topersons of ordinary skill in the art.

However, when in AUTO DCP mode, the chip attempts to provide a maximumcurrent, and may request 1.5-2.0 A by using internal switches andresistors. In a case where the charging device can't have more than 1 A,the microprocessor 51 then switches U3 to the CDP mode, and in thismode, internal resistors are not connected. Instead, DM_IN is connectedto DM_OUT and DP_IN is connected to DO_OUT. Thus, the D+/D1 bus isattached to the external divider R2,R19,R21,R22. The value of suchresistors is selected so as to communicate to the attached device thatmore than 1 A current is not permissible.

R18 set overcurrent protection at about 2.4 A to prevent chip fromthermal damage.

The circuits 52, 54, and 56 include respective resistive voltage dividernetworks and microchips including pin configurations that are, otherthan nomenclature, identical to the resistive voltage divider network 58and microchip U2. Accordingly, the resistive voltage divider networksand microchips associated with the circuits 52, 54, and 56 are notdescribed in detail. As can be appreciated, the microprocessor 51communicates with the circuits 52, 54, and 56 in a manner as describedabove with respect to the circuit 50.

The microprocessor 51 is configured to enumerate the connectedelectronic devices and communicate to each of the enumerated electronicdevices the device charging current available through its respective lowvoltage port connection. Thus, the microprocessor 51 informs theconnected electronic devices of a maximum amount of current available,but allows the connected electronic devices to determine an amount ofcurrent to draw from the low voltage ports 30, 32, 34, and 36. Inembodiments, the enumerated electronic devices themselves initiatedistribution of the low charging current from the low voltage ports 30,32, 34, 36. This prevents constant cycling, which can be caused bypossible “wake up” when the portable device is switched to dischargemode, between the low voltage ports 30, 32, 34, and 36. This initialdetection is achieved by sensing current (e.g., current through one ofthe first and second resistive branches 60, 62 of the resistive circuit58) from the low voltage port 30. Therefore, the microprocessor 51 doesnot regulate or control the flow of current to the enumerated electronicdevices. Instead, the enumerated electronic devices themselves decide onhow much current to draw from the maximum current available (indicatedor computed by the microprocessor 51). In other words, the enumeratedelectronic devices are self-regulated. The microprocessor 51 isconfigured to continuously re-enumerate and redetermine as one or moreof the electronic devices or portable devices are connected/disconnectedto/from the plurality of voltage ports 30, 32, 34, 36.

USB standard 2.0 provides for the low voltage output ports 30, 32, 34,and 36 to provide power to attached portable devices at a nominal value.In embodiments, the multiport USB charging device 10 may provide up to10 W of power. Thus, in this embodiment, each of the low voltage ports30, 32, 34, 36 is capable of providing up to two (2) amps of chargingcurrent, that is 10 W/5V=2 A. This 2 A of charging current may bedistributed evenly among the four (4) low voltage ports 30, 32, 34, and36 to provide up to 500 mA to four (4) portable devices attached to thelow voltage ports 30, 32, 34, and 36.

In embodiments, such as, for example, when the multiport USB chargingdevice 10 is configured to provide up to 20 W of power, each of the lowvoltage ports 30, 32, 34, and 36 is capable of providing 1.0 A ofcharging current to four (4) portable devices attached to the lowvoltage ports 30, 32, 34, 36. As can be appreciated, the amount ofcharging current that can be provided by the low voltage ports 30, 32,34, 36 can be altered to accommodate other power requirements and/orcharging current protocols.

In embodiments, such as the illustrated embodiment, the microprocessor51 may be configured to provide power supply protection to ensure thatthe power supply does not fall below the nominal limit. When thisoccurs, it is considered an overload condition. In this particularembodiment, a junction J5 (FIG. 3) is provided and includes a pin 1 thatis electrically connected to the 5V power supply and pin 3 that iselectrically connected to GND. A pin 2 of the junction 5 is electricallyconnected to a PD1 pin 26 of the microprocessor 51 and a pin 4 of thejunction 5 is electrically connected to NRST pin 1 of the microprocessor51. Logic circuitry associated with the pin 2 generates a SWM signalthat is output to PD1 pin 26 of the microprocessor 51 and logiccircuitry associated with the pin 4 generates a NRST signal that isoutput to the NRST pin 1 of the microprocessor 51. When themicroprocessor 51 detects the SWM signal and NRST signal, themicroprocessor 51 switches to a disconnect mode that disables the lowvoltage ports 30, 32, 34, 36.

In other words, pin 1 is a reset pin for this particularmicrocontroller. To measure voltage in this particular exemplaryembodiment, the input of the AD converter (pin 16) is connected to pin5, which is the output of the internal 1.8V linear regulator inside thechip. All AD converter readings are referenced to the input V+, which isthe common power supply output. However, VCAP is stable because ofinternal regulations. When a, e.g., 5V power supply goes down, thereading of the VCAP goes up, and this can be used to measure the inputin reference to the stable VCAP voltage. Moreover, it is noted that pin26 is used to monitor the output level and shuts down the device when anovervoltage condition is detected.

Operation of the multiport USB charging device 10 is now described. Forpurposes of this description, the multiport USB charging device 10 isassumed to include a 20 W power supply that provides up to 4 A ofcharging current.

The multiport USB charging device 10 may be used to charge one ormultiple portable devices. For example, in embodiments, the multiportUSB charging device 10 may be used to simultaneously charge four (4)portable devices (e.g., four (4) tablets “T”) attached to the multiportUSB charging device 10.

Initially, a first tablet “T” may be attached to one of the low voltageports, e.g., low voltage port 30. For illustrative purposes, the firsttablet “T” is defaulted to request 2 A of charging current when attachedto the multiport USB charging device 10. Upon detection of the firsttablet “T” being attached to the low voltage port 30, the microprocessor51 allows the first tablet “T” to draw the requested 2 A of chargingcurrent from the low voltage port 30, as this charging current is withinthe charging current capacity of the multiport USB charging device 10.It is noted that the first tablet “T” may draw the maximum current, asdetermined by the microprocessor 51, or may draw a current less than themaximum current. Thus, the first tablet “T” itself may determine howmuch current to draw and need not necessarily draw the maximum amount ofcurrent available as indicated by the microprocessor 51.

Thereafter, a second tablet “T” may be attached to one of the other lowvoltage ports, e.g., low voltage port 32. Again, the microprocessor 51allows the second tablet “T” to draw the requested 2 A of chargingcurrent from the low voltage port 32, as the combined charging currentrequest of the two (2) tablets “T” is within the charging currentcapacity of the multiport USB charging device 10, i.e., 4 A. Once again,the second tablet “T” may draw any amount of current it desires, up tothe maximum current available, as computed by the microprocessor 51.Thus, the microprocessor 51 does not dictate the amount of current eachtablet “T” should draw. Instead, each tablet “T” can make thatdetermination for itself.

In the instance, where third and fourth tablets “T” are attached to theremaining low voltage ports, e.g., low voltage ports 34 and 36, each ofthe third and fourth tablets “T” will also request 2 A of chargingcurrent from the respective low voltage ports 36 and 38. Themicroprocessor 51, however, detects this request and communicates withthe four tablets “T” via the data pins of the microchips associated withthe low voltage ports 30, 32, 34, and 36 to renegotiate the chargingcurrent request of the four (4) tablets “T.” Specifically, themicroprocessor 51 communicates with the four (4) tablets “T” to changetheir initial current charging request from 2 A to 1 A, which is withinthe 4 A charging current capacity of the multiport USB charging device10. Therefore, the microprocessor 51 indicates what the maximum amountof current is to each of the tablets “T,” and based on this information,each tablet “T” decides on how much current to draw.

Once one of the four (4) tablets “T” is fully charged (or unattachedfrom the multiport USB charging device 10), the microprocessor 51re-communicates with the remaining attached tablets “T” and againrenegotiates charging current requests with the remaining attachedtablets “T”. For example, if two (2) of the four (4) tablets “T” areunattached from the multiport USB charging device 10 and the two (2)remaining tablets “T” are still charging, the microprocessor 51 willallow each of the two (2) remaining attached tablets “T” to draw 2 A ofcharging current until the remaining tablets “T” are fully charged.Therefore, the microprocessor 51 is configured to continuouslyre-enumerate and redetermine as one or more of the electronic devices orportable devices are connected/disconnected to/from the plurality ofvoltage ports 30, 32, 34, 36.

As can be appreciated, the microprocessor 51 follows the same controlprotocol regardless of the number of portable devices that are attachedto the multiport USB charging device 10 to ensure that the total currentcharging request of the attached portable device(s) does not exceed themaximum charging current capacity of the multiport USB charging device10. However, it is noted that the charging current is dictated by thetablets' own self-regulation, which in turn is based on the amount ofavailable current the microprocessor 51 has indicated as available.

The multiport USB charging device 10 overcomes the aforementioneddrawbacks that are typically associated with conventional multiport USBcharging devices. That is, because microprocessor 51 renegotiatescharging current requests from an attached portable device as opposed tolimiting current to the port attached to the portable device, thelikelihood of one of the components of the multiport USB charging device10 overheating is eliminated and, thus, the chances of the multiport USBcharging device 10 shutting down during operation reduced.

The multiport USB charging device can also provide for intelligentcurrent distribution, which can speed up and optimize the chargingprocess. Examples of such features would be keeping the last connectedport as a high priority and trying to provide a highest possible outputon this port, or increasing an output current on some of the connecteddevices after other devices complete their charging.

In summary, the microprocessor is configured to enumerate the connectedelectronic devices and communicate to each of the enumerated electronicdevices the device charging current available through its respective lowvoltage port connection. Moreover, the available device charging currentfor each enumerated electronic device is determined by themicroprocessor as a function of the total charging current and theenumerated electronic devices. As one or more of the electronic devicesare connected/disconnected from the plurality of low voltage ports, themicroprocessor is configured to re-enumerate the connected electronicdevices and communicate to each of the re-enumerated electronic devicesa redetermined device charging current available through its respectivelow voltage port connection. The available redetermined device chargingcurrent for each re-enumerated electronic device is determined by themicroprocessor as a function of the total charging current and there-enumerated electronic devices. As a result, the microprocessor isconfigured to continuously re-enumerate and redetermine as one or moreof the electronic devices are connected/disconnected to/from theplurality of low voltage ports.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, the multiport USB charging device 10 may beconfigured to provide a visual indication of the charge status (i.e.whether all portable devices are charged or whether one or more of theportable devices is/are still charging) via USB port state indicators(not shown). In embodiments, the port state indicators may include, forexample, a colored (e.g., a yellow) Light Emitting Diode (LED) which isilluminated when one or more of the portable device connected to themultiport USB charging device 10 is not fully charged, and may include,for example, a green LED which is illuminated to indicate that allportable device connected to the multiport USB charging device 10 arefully charged.

In embodiments, when the multiport USB charging device 10 is connectedto an external power source, a power indicator (not shown) may beilluminated to provide visual verification that the multiport USBcharging device 10 is operational. The power indicator may beimplemented using, for example, a blue LED or other visual indicator.

In embodiments, the multiport USB charging device 10 may be included asa component of an outlet configuration. Such an outlet configuration mayinclude, for example, the multiport USB charging device 10, a receptacle(e.g., a GFI receptacle), a coaxial connection, a cat 5 connection,etc., or combination thereof.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. A universal serial bus charging device forcharging connected electronic devices, comprising: a microprocessor; apower supply configured to output a total charging current; and aplurality of low voltage ports in communication with the microprocessorand electrically coupled to the power supply, each of the plurality oflow voltage ports being capable of connecting with the electronicdevices and providing the electronic devices a device charging current,wherein the microprocessor is configured to enumerate the connectedelectronic devices and communicate to each of the enumerated electronicdevices the device charging current available through its respective lowvoltage port connection, wherein the available device charging currentfor each enumerated electronic device is determined by themicroprocessor as a function of the total charging current and theenumerated electronic devices.
 2. The universal serial bus chargingdevice according to claim 1, wherein, as one or more of the electronicdevices are connected/disconnected from the plurality of low voltageports, the microprocessor is configured to re-enumerate the connectedelectronic devices and communicate to each of the re-enumeratedelectronic devices a redetermined device charging current availablethrough its respective low voltage port connection.
 3. The universalserial bus charging device according to claim 2, wherein the availableredetermined device charging current for each re-enumerated electronicdevice is determined by the microprocessor as a function of the totalcharging current and the re-enumerated electronic devices.
 4. Theuniversal serial bus charging device according to claim 1, wherein themicroprocessor is configured to continuously re-enumerate andredetermine as one or more of the electronic devices areconnected/disconnected to/from the plurality of low voltage ports. 5.The universal serial bus charging device according to claim 1, whereinthe plurality of low voltage ports include a microchip which isconnected to a resistive voltage divider network.
 6. The universalserial bus charging device according to claim 5, wherein the resistivevoltage divider network includes a first resistive branch including atleast one resistor and a second resistive branch including at leastthree resistors.
 7. The universal serial bus charging device accordingto claim 6, wherein logic circuitry associated with the first resistivebranch is configured to ensure that the current does not exceed amaximum current threshold.
 8. The universal serial bus charging deviceaccording to claim 6, wherein logic circuitry associated with the secondresistive branch is configured to ensure that the current does not fallbelow a minimum current threshold.
 9. The universal serial bus chargingdevice according to claim 1, wherein the microprocessor is programmed tomeasure voltage of the power supply of the universal serial bus chargingdevice such that if a voltage output of the power supply falls below anominal value, the microprocessor either disconnects one or more of theplurality of low voltage ports or switches to a disconnect mode.
 10. Amultiport universal serial bus charging device for charging connectedelectronic devices, comprising: a microprocessor; a power supplyconfigured to output a total charging current; and a plurality of lowvoltage ports each in communication with the microprocessor andelectrically coupled to the power supply, wherein the microprocessor isconfigured to enumerate the connected electronic devices and communicateto each of the enumerated electronic devices a device charging currentavailable through its respective low voltage port connection.
 11. Themultiport universal serial bus charging device according to claim 10,wherein each of the low voltage ports of the plurality of low voltageports includes a microchip connected to a respective resistive voltagedivider network.
 12. The multiport universal serial bus charging deviceaccording to claim 11, wherein the respective resistive voltage dividernetworks include a first resistive branch including at least oneresistor and a second resistive branch including at least threeresistors.
 13. The multiport universal serial bus charging deviceaccording to claim 12, wherein the device charging current is a currentmeasured along the second resistive branch of the respective voltagedivider networks.
 14. The multiport universal serial bus charging deviceaccording to claim 12, wherein logic circuitry associated with the firstresistive branch of the respective voltage divider networks isconfigured to ensure that the current does not exceed a maximumthreshold.
 15. The multiport universal serial bus charging deviceaccording to claim 12, wherein logic circuitry associated with thesecond resistive branch of the respective voltage divider networks isconfigured to ensure that the current does not fall below a minimumthreshold.
 16. The multiport universal serial bus charging deviceaccording to claim 10, wherein the power supply is configured to provideten (10) watts of power and two (2) amps of charging current.
 17. Themultiport universal serial bus charging device according to claim 10,wherein the plurality of low voltage ports includes first and second lowvoltage ports, each of the first and second low voltage ports capable ofproviding one (1) amp of charging current to electronic devices attachedthereto.
 18. The multiport universal serial bus charging deviceaccording to claim 10, wherein the power supply is configured to providetwenty (20) watts of power and four (4) amps of charging current. 19.The multiport universal serial bus charging device according to claim18, wherein the plurality of low voltage ports includes first, second,third, and fourth low voltage ports, each of the first, second, third,and fourth low voltage ports capable of providing one (1) amp ofcharging current to electronic devices attached thereto.
 20. Themultiport universal serial bus charging device according to claim 10,wherein the microprocessor is programmed to measure voltage of the powersupply of the multiport universal serial bus charging device such thatif a voltage output of the power supply increases above the specifiedrange the microprocessor either disconnects one of the plurality of lowvoltage ports or switches to a disconnect mode.
 21. A method forcharging multiple portable devices attached to a multiport universalserial bus charging device, comprising: comparing a charging currentdraw from the multiple portable devices attached to the multiportuniversal serial bus charging device with a maximum charging currentcapacity of the multiport universal serial bus charging device; and ifthe combined charging current draw from the multiple portable devices isgreater than the maximum charging current capacity of the multiportuniversal serial bus charging device, renegotiating the charging currentdraw of at least one of the portable devices so that the combinedcharging current draw from the multiple portable devices does not exceedthe maximum charging current capacity of the multiport universal serialbus charging device.